In "Your Health" today, the dangers of inactivity. First, we'll talk about chronic sitting. Now, we all know that being physically active is good for you, but now researchers are finding that even if you spend some time for regular exercise, sitting all day in front of a computer, say - or a microphone -can still cause health problems. NPR's Patti Neighmond reports.

PATTI NEIGHMOND: Danielle Osby(ph) says the best birthday gift ever was her bicycle. Co-workers chipped in to surprise her about this time last year - a brilliant-colored cruiser.

Ms. DANIELLE OSBY: She's green, sassy, and good for you.

NEIGHMOND: So after being mostly sedentary for years, Osby now bikes back and forth to work, about 10 miles a day.

Ms. OSBY: I'm not the one that kind of like, monitors myself on the scale constantly, but I've dropped a nice amount of weight.

NEIGHMOND: And at 41, Osby's blood pressure is good, her cholesterol's low, and she's successfully battling a family history of hypertension and diabetes. All good - but with one hitch. Like many of us, when Osby's not sleeping or biking, she's often working - and, as she says, completely handcuffed to her desk.

Ms. OSBY: If there's a progress report due or a there's a grant due or some other deadline, the time kind of flies by while you're sitting, sitting, sitting - at the computer, sitting.

NEIGHMOND: Researchers are now beginning to suspect that even though Osby exercises every day, it may not be enough to counteract the hazards of all that sitting. Because when you add it all up, epidemiologist Steven Blair says it's a lot more sitting than moving.

Dr. STEVEN BLAIR (Epidemiologist): Let's say you do 30 minutes of walking, five days a week. And let's say you sleep for eight hours. Well, that still leaves 15 and a half hours. Well, an awful lot of us have sedentary jobs, and we sit there at our job or watching television - or just spend most of the day sitting.

NEIGHMOND: Blair works at the University of South Carolina and headed a study looking at adult men and their risk of dying from heart disease. He calculated how much time the men spent in their cars, at their desk, in front of the TV.

Dr. BLAIR: And those who were sitting more were substantially more likely to die.

NEIGHMOND: Despite the fact that many of them routinely exercised. Blair says scientists are just beginning to learn about the risks of a mostly sedentary day.

Dr. BLAIR: If you're sitting quietly, your muscles are not contracting, except perhaps those you're using to type on your computer. But the big muscle groups -like in your legs and back, and so forth - are sitting there pretty quietly.

NEIGHMOND: And because the muscles aren't moving, metabolism slows down.

Dr. BLAIR: When we look at waist circumference, we look at triglycerides, we look at fasting blood glucose, we're finding that people who sit more have less desirable levels.

NEIGHMOND: Which increases the risk of diabetes, heart disease, and a number of health problems.

Dr. TONI YANCEY (UCLA): We just aren't really structured to be sitting for such long periods of time. And when we do that, our body kind of goes into shutdown.

NEIGHMOND: Dr. Toni Yancey�specializes in health promotion at UCLA's School of Public Health. For years, she's worked on developing programs to motivate people to get up and move, even while they're at their desks.

Dr. YANCEY: Sitting on a ball rather than a chair. As a matter of fact, that's what I'm doing right now. And you know, it kind of helps you strengthen your core. It helps you with your balance and flexibility.

NEIGHMOND: And try to take a 10-minute exercise break, like a brisk walk twice a day. Or, as Yancey says, just get up every so often and stretch.

Dr. YANCEY: We can put in a prompt in our computer to encourage us to stand up every hour, and just move around a little bit.

NEIGHMOND: It may not sound like much, but one Australian study found that these types of mini-breaks - just one minute long throughout the day - actually made a difference. Just standing up and moving - like taking a step, marching in place every hour or so - actually lowered blood sugars, triglycerides, cholesterol, and even waist size.

Dr. YANCEY: If there's a fountain of youth, it probably is physical activity. So the problem is not whether it's a good idea. The problem is how to get people to do more of it.

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